Blues or orange, that is the usual in UK
As above.
I really don't get this current forum fashion for either tiny gauge needles, stupidly short needles for IM, fear over oil volume etc.
I've been jabbing for pushing 20 years. For the first 10, I used 23g exclusively. Since then it's been both 23g (blue) & 25g (orange).
I wouldn't dream of going shorter than 1' for delts, let alone quads. I always push the base of the needle firmly into the flesh to limit wiggling & to prevent changing the injection depth - you will not hit bone with 1’ unless you’ve just stepped out of Auschwitz.
I've never had a problem with up to 2ml in delts, 3ml in quads. That said, I prefer 1.5ml & 2.5ml respectively.
Guess what? In all that time I've never had a post-injection problem & I have no evidence of scar tissue, despite using only delts & quads.
@Johnylee - my advice, FWIW:
1: Use 2-3ml syringes over 1ml. The narrower the barrel, the higher the pressure the oil is being injected under - this in itself can cause trauma.
2: No need to go below 25g for IM, use 23g for really viscous oils. The narrower the needle bore, the higher the pressure - compounds the trauma issue with #1
3: Inject as slow as possible.
4: Avoid leur-locks. A correctly fitted slip-tip needle blowing off the end of a syringe is nature's way of telling you that there's too much pressure build up inside the barrel - again, a leur-lock being unable to blow off is a likely cause of trauma, compounded by both #1 & #2.